The overall objectives of this work include: (1) The study of tyrosinases in the skin of albino animals and hair bulbs of human albinos. (2) The measurement of tyrosinase in the foreskin of newborns and elucidation of racial differences. (3) Mechanistic studies on mammalian and bacterial tyrosinases (dopa and tyrosine binding). 4. Isolation of tyrosinases from pigmented mouse skin. (5) A study of the relationship, if any, between plasma levels of MSH and tyrosinase activities in skins.